This disclosure relates to a vacuum insulating glazing (VIG) unit. In particular, it relates to the vacuum evacuation head (also known as all metal cup). And sealing of the evacuation tube with a heater inside the evacuation head.
Vacuum insulating glazing (VIG) units typically comprise two glass panes spaced by pillars, sealed at the periphery and having an evacuated interior void. The void is evacuated with an evacuation head through a hole in the pane to a pressure such as 1E-6 bar.
US2006175767 discloses a VIG unit and an evacuation head being 70 mm. The disclosure deals with a gasket to ensure a good seal. Paragraph [0061] does mention an evacuation head diameter of 50 mm to 100 mm.
US20120148795 deals with the sealing of the evacuation hole. It discloses a prior art evacuation tube and evacuation head with a coil heater (FIG. 2a) which is used to melt the tube tip (also known as the tip off).